1. Field of the Invention
The invention relates to the passage of hydraulic pigging systems through pipelines and other conduits. More particularly, it relates to a water pumper facilitating the movement of pig devices through such lines.
2. Description of the Prior Art
Pigging systems are commonly employed in order to clean or condition the inside surfaces of pipelines or other conduits. In normal pigging operations, a high flow of a propelling fluid is required at moderate pressure levels. During movement of the pig device through a line, however, the resistance to travel occasionally increases. Such increased resistance may be due to a variety of factors. During cleaning operations, the most common cause is the encountering of the pig with a thicker deposit on the wall of the line. This resistance to travel causes the pig to slow down or even to stop in the line. The propelling pressure then required to move the stuck pig forward, even at a slower rate, can be several times higher than the normal pressure required to move the pig before it became stuck in the line.
Centrifugal pumps commonly used to propel a pigging system through a line are capable of delivering high water or other liquid flow at a moderate pressure level, typically on the order of 300 psi. If higher pressures are required when using the typical centrifugal pump approach, identical pumps are commonly employed in series in order to achieve the desired higher flow pressure. For example, two centrifugal pumps of 300 psi capacity would be connected for series flow to get a 600 psi pressure level, three such pumps would be piped in series to obtain a 900 psi pressure, and the like. Higher flow rates would be accomplished with a larger impeller unit or by adding additional pumps in parallel. Operating in this manner, the pump system is sized for the maximum flow rate desired, and additional stages are added in series to achieve the maximum pressure desired for a particular operating circumstance.
Such practice of sizing a pumping system to deliver both the maximum required flow and the maximum required pressure results in a larger, and hence more expensive, pumping system than would be required for either the maximum flow or the maximum pressure alone. The use of a larger pump also requires the use of a more powerful driver and associated higher capital and operating costs.
There is a genuine desire in the art, therefore, for improved pumpers for the passage of pigging systems through lines. More particularly, it is desired to enable pigging operations to be carried out using less expensive pumping equipment capable of conveniently satisfying the unique problems encountered in pigging operations.
It is an object of the invention to provide a water or other fluid pumper suitable for use with hydraulic pigging systems.
It is another object of the invention to provide a water or other fluid pumper system capable of advantageous use in propelling a pigging device through a line and overcoming resistance to travel of said device.
With these and other object in mind, the invention is hereinafter described in detail, the novel features of the invention being particularly pointed out in the appended claims.